SARS-COV-2 VIRUS INFECTED PATIENT IDENTIFICATION THROUGH CANINE OLFACTIVE DETECTION ON AXILLARY SWEAT SAMPLES

Facing the COVID-19 pandemic, testing individuals in order to promptly isolate positive people is one of the key actions. One approach to rapid testing might be to consider the olfactory capacities of trained detection dogs in order to develop a non-invasive, rapid and cheap mass detection approach, through the Volatile Organic Compounds (VOCs) signature of SARS-CoV-2 infection. The goal of this study was to determine the individual values of sensitivity and specificity of trained dogs when performing olfactory detection of COVID-19 on axillary sweat samples. Seven dogs were used to sniff a total of 218 samples (62 COVID-19 positive and 156 COVID-19 negative samples), based on a randomised and double-blinded protocol carried out on olfaction cone line-ups. To ensure a wide olfactory range as close as possible to operational conditions, the samples were retrieved from 13 different sites. Sensitivities varied from 87% to 94% for 6 dogs, and were above 90% for 3 of them. Only one dog, whose sensitivity was 60%, was not selected to subsequently enter the operational stage. Specificities varied from 78% to 92%, with 6 dogs over 85% and 4 dogs over 90%. Based on the calculated sensitivity and specificity for each dog, positive and negative predictive values (PPV and NPV) were calculated according to several prevalence rates of SARS-CoV-2 scenarii, and were compared to PPV and NPV of an "almost perfect" diagnostic tool. For 6 out of the 7 dogs, and for a prevalence rate of SARS-CoV-2 lower or equal than 40%, the NPV of the dogs were virtually the same as the one of the "almost perfect" tool. Along with other studies on olfactory detection of COVID-19 by dogs these positive and encouraging results suggest that olfactory dogs may play an important part in mass COVID-19 pre-testing situations.

Evaluating ten commercially-available SARS-CoV-2 rapid serological tests using the STARD (Standards for Reporting of Diagnostic Accuracy Studies) method.

Numerous SARS-CoV-2 rapid serological tests have been developed, but their accuracy has usually been assessed using very few samples, and rigorous comparisons between these tests are scarce. In this study, we evaluated and compared 10 commercially-available SARS-CoV-2 rapid serological tests using the STARD methodology (Standards for Reporting of Diagnostic Accuracy Studies). 250 sera from 159 PCR-confirmed SARS-CoV-2 patients (collected from 0 to 32 days after onset of symptoms) were tested with rapid serological tests. Control sera (N=254) were retrieved from pre-COVID periods from patients with other coronavirus infections (N=11), positive rheumatoid factors (N=3), IgG/IgM hyperglobulinemia (N=9), malaria (n=5), or no documented viral infection (N=226). All samples were tested using rapid lateral flow immunoassays (LFIA) from ten manufacturers. Only four tests achieved [≥]98% specificity, with other tests ranging from 75.7%-99.2%. Sensitivities varied by the day of sample collection, from 31.7%-55.4% (Days 0-9), 65.9%-92.9% (Days 10-14), and 81.0%-95.2% (>14 days) after the onset of symptoms, respectively. Only three tests evaluated met French Health Authorities' thresholds for SARS-CoV-2 serological tests ([≥]90% sensitivity + [≥]98% specificity). Overall, the performances between tests varied greatly, with only a third meeting acceptable specificity and sensitivity thresholds. Knowing the analytical performance of these tests will allow clinicians to use them with more confidence, could help determine the general population's immunological status, and may diagnose some patients with false-negative RT-PCR results.

Lung injury in patients with or suspected COVID-19 : a comparison between lung ultrasound and chest CT-scanner severity assessments, an observational study

BackgroundChest CT (CT) is the reference for assessing pulmonary injury in suspected or diagnosed COVID-19 with signs of clinical severity. We explored the role of lung ultrasonography (LU) in quickly assessing lung status in these patients. MethodseChoVid is a multicentric study based on routinely collected data, conducted in 3 emergency units of Assistance Publique des Hopitaux de Paris (APHP); 107 patients were included between March 19, 2020 and April 01, 2020 and underwent LU, a short clinical assessment by 2 emergency physicians blinded to each others and a CT. LU consisted of scoring lesions in 8 chest zones from 0 to 3, defining a severity global score (GS) ranging from 0 to 24. CT severity score ranged from 0 to 3 according to the extent of interstitial pneumonia signs. 48 patients underwent LU by both an expert and a newly trained physician. FindingsThe GS showed good performance to predict CT severity assessment of COVID-19 as normal versus pathologic: AUC=0.93, maximal Youden index 1 with 95% sensitivity, and 83% specificity. Similar performance was found for CT assessment as normal or minimal versus moderate or severe (n=90): AUC 0.89, maximal Youden index 7 with 86% sensitivity, and 78% specificity. Good agreement was found for zone scoring assessed by new trainee (30mn theory + 30mn practice) and expert (n=14,14*8 checkpoints), weighted kappa 0.85-1; moderate agreement was found for new trainee (n=48, 30mn theory) and expert, kappa 0.62-0.81. InterpretationGS score is a simple tool to assess lung damage severity in patients with suspected or diagnosed COVID-19. Comparing the performance of new trainees and expert physicians opens a path for adoption beyond the scope of experts. LU is a good candidate for patients triage, especially in case of CT availability issues.